Hi Guys...
I've recently replaced head gaskets and on completion, when I came to start up she's running rough as hell and making some smoke before stopping. On a previous post I had assumed I may have got the valve timing wrong but all checks out ok here. I've had a computer on it and again showing no faults. The car ran ok before I did this work... what did I do wrong?? ...somebody please tell me!!
Warrick.

 

Compression test first off.

 

Thanks Sean, just removed new spark plugs...they are all black and sooty...what do you reckon?

 

Also compressions test perfect...

 

They should be grey with brown edge. I've already suggested an air leak upstream of the MAF.
I'd be looking at the TB seal, top and bottom. No codes?

Fuel pressure OK?
Crank position sensor clean?
Cam position sensor plugged in?
It's basics to confirm I know, but without codes that's the route I'd be taking...

 

Hi Sean, yep, they all check out OK... I'm thinking maybe I could have wrongly connected pipework somewhere on the throttle body? or maybe dirty fuel supply, though it was running perfect before I started the head gasket work.
Warrick.

 

Hi Sean, having re-assembled everything and started up again, still with the problem, I'm now getting error codes on the scanner:
P0102 Mass air flow A circuit low.
P0112 Intake air temperature sensor 1 circuit low.
Warrick.

 

MAF sounds bust or not connected properly, double check the connection and wiring.

 

Cleaned the MAS air connection and now there are no error codes.

 

Hi everyone.
It's been suggested that because the electric fans are going berserk during idle and that there may be over fuelling, that this all may come down to a bad earth on the engine?
Maybe I missed connecting something when rebuilding the heads... any suggestions??

 

Did you dis/re-connect up the earth under the car parallel to the bell housing? I'd check this first, then the two big black cables running along either inner front wing to their terminals, one to the brake pedal housing and the other to the fuse boxes. Earth points behind each headlight, ring terminals and dome headed nuts also check.
Also check the engine harness for grounds - alt/starter/air-con etc...

You getting a battery drain?

 

Hi Sean,
I didn't disturb the earth strap at the bell housing when I replaced the head gaskets and have checked all the other earth points you mentioned. All seems OK.
'Alldata' show an 'Engine Ground Screw' situated around the front nearside engine compartment. I'd hoped it may have been on a head, buried under the supercharger/air cooler and so I've stripped it back down to the inlet manifolds again...can't see the 'engine earth screw' under here, any ideas? Neither are there any obvious connections that I may have missed...what to do, rebuild again?
Sorry to continue to sound so unhappy!
Warrick.

 

Well- since you already have it torn down, turn the engine so the cam flats are flat, put in the flex plate holding tool and check that they are all correct- then work your way through reassembly double checking every connection and seal on the way. should take no more than 2 hours and you can check off potential problems as you go!

 

Hello everyone,
With the crankshaft locked in position, is correct to set up and tighten all four camshafts in this state or should I set up the camshafts on bank 1 then turn the crankshaft one full turn then set up the camshafts on bank 2?
Thanks, Warrick.

 

No need to turn the engine once locked up at the crank, this is the standard service position at 45 degrees after top dead centre for these engines, just confirm cam timing on each bank and button it up.

Why did the engine need head gaskets? What are the compressions on each cylinder?

Did you find anything amiss like a badly connected coil, oil in a plug well etc on the strip down?

 

Fan relay location....(remote possibility it's failed in the full on position) to disconnect pull the inner wheel arch out of the way

Fans running full on can mean a dead thermostat, or (temp sensor as discussed) If the sensor is tested good, my gut feeling is t-stat. It might have just failed after the initial work on the engine? £10 part...

 

Hi Sean, once again many thanks for your interest and help!
So, today I have meticulously re built the top end, carefully paying attention to all multi plug connections and air tight joints. I dried out the plugs (on my ex wife's gas cooker) and started her up (the Jag!) ... no improvement.
I took your advice Sean and went around the usual air leak suspects with the gas, to no avail, no increase in revs.
To recap, I have checked compressions.. all 8 cylinders at 8 bars, 120lb/sq ins.
I have double checked the camshaft settings.. all four flats horizontal with flywheel locked.
I have checked fuel for purity and pressure (43lbs/sq ins).
Air filter is clean.
From the work I've done re building these last two days, I'm pretty sure there's no air leak.
There has been the odd fault thrown up during this work but it's been down to a bad connection at a plug during re build. There are no faults shown on the scanner now despite the ongoing running problem.

The symptoms are that there is immediate over fuelling and flooding on start up, any movement on the accelerator pedal and she stops, cooling fans operating intermittently ...and the owner is suffering with depression, anxiety and panic attacks.
Help..please?

 

Ok- battery is fresh/new? Check bulkhead connector. Undo battery, touch cables together to clear brain. Unplug MAF to see if there is any change with it unplugged. also, start without touching the accelerator pedal and let it work through the gyrations.

This *sounds* like an electrical issue to me now. (compression good, cam timing correct, spark and fuel)

 

OK, thanks, did this check also... no difference.

 

"The symptoms are that there is immediate over fuelling and flooding on start up, any movement on the accelerator pedal and she stops, cooling fans operating intermittently"

How do you know it is flooding? If you are smelling fuel, then spark would be the next thing to check.

Also- it is very helpful if you list WHAT you did as you do it so it can be checked off the list, and ESPECIALLY the specific results.

EX: 120lbs across all cylinders is not likely- you will have SOME variation and that is sometimes helpful to know. If your battery is 18 months old, and not brand spanking new, that is helpful to know. etc. etc. Not trying to give you a hard time, but detailed information will get you to a resolution MUCH faster.